Speed and course indicator for conveyances



Aug 11.7 19%. 3,59%,380

F. G. SIMPSON SPEED AND COURSE INDICATOR FOR CONVRYANCES Filed Augus 4, 1923 2 Sheets-Sheet 1 -l L i l dim 4% Aug, 17 1926. 11,596,380

F. G. SIMPSON SPEED AND COURSE INDICATOR FOR CONVEYANC ES Filed August 4; 1923 2 Sheets-Sheet 2 3114161 1 f or vlq'ederzk 6/021 922,050

' ercise of this method.

patented ding l d, T9260 FREDERICK GRANT SI'MESON, @1 3 SEATTLE, WMHTNGTGN.

srnnn Jinn connsn rnnrcnrcn son convnrnavcns;

application filed August a. 192 3. serial no, cam-a7.

This invention relates to a method of, and apparatusfor, measuring the velocity, and indicating the direction of motion, of a terrestrial body relative to the surface of the earth; and, more specifically, embodies means of determining the rate at which the vertical component of the earths magnetic field is cut by an electrical conductor which forms a part of such moving terrestrial body.

The object of the invention is to provide a simple, and easily applied, method of ascertaining the velocity and its direction relative, and parallel, to the earths surface, of any conveyance which is capable of carrying such devices as are necessary in the ex- A more particular object of the invention is to provide means for determining the speed over the surface of the earth, and the course, of conveyances such as aircraft and watercraft. The direction in which the conveyance is headed must he determined by a compass and the drift angle, or angle at which the conveyance is actually proceeding relative to the direction in which it is headed is determined. by this apparatus thus furnishin the neces: sary information for'determinmg the true course. i

These objects are accomplished by providing, on the conveyance, an arrangement of electrical circuits wherein electromotive forces are generated by, and are proportion al to, the movement of the conveyance in any direction, in a plane substantially parallel to the earths surface, which is to say, at an angle of-ninety degrees from the direction of the vertical component of the earths magneticfield, and by providing means for measuring such electromotive forces; all as will be understood from the following description in connection with themeral 1 represents two conductor plates of" accompanying drawings.

In the drawings Figure 1 illustrates, dia

grammatically, a ty ical form of my arrangement of electrical circuits, and electrical apparatus, on a conveyance. Figure 2 shows in perspective one, of many, ways of assembling the various circuits, and apparatus, on a conveyance Like reference numerals designate like parts throughout'the several views.

Referring particularly to Fig. l, the nuan electricalcondenser. The plates '1 are rigidly attached to the respective extremities 'tationof the condenser plates labont the of the insulating arm 2. The'arm 2 with its surrounding atmosphere forms the dielectricof the condenser of which the plates 1 are the conductors. The arm 2 is attached at to its middle point to the revolving shaft 4 of the electric motor 5. The numeral 11 represents two branches of an electrical conductor in the form of a wire, or rod, of small cross sectional area compared to its length. Tnserted in series with the conductor 11 is the inductance coil 26. The two branches of the conductor 11 lie in the same vertical and horizontal planes; A. brush holder 12 is electrically. attached to each of the outer extremities of the conductor 11. A brush 13 is electrically attached to each i of the brush holders 12. The distance between the brushes 13 is the-length of a diameter of the circumference formed oy the rocenter of the shaft 4:. The relative posi tions of the condenser plates 1 and the brushes 13 are such as to cause each of the plates 1 to make electrical contact with each of the brushes 13 for short time interval once during each revolution of the shafi a. The numerals 27 and 29 represent two triode electron relay tubes. Each tube consists of an anode, a hot cathode and a grid electrode placed -hetween the anode and the cathode, contained in an evacuated chamber in awell known manner. The cathodes of v the tubes 2? and 29 are filament conductors arranged to be heated by an electric current. The terminals ofthe filaments, which constitute the cathodes, are electrically connected to form two common terminals, and to the terminals of the electric hattery 31 which supplies the necessary current to heat the filaments. 30is an electric battery or other generating source of electromotive force. V 24 is an electric. current, or electric potential, indicating --instrument. 28 is a transformer having a primary coil and a secondary coil. The negative terminal of the battery 30 is electrically connectedto the negative terminal "of the battery 31 and, therefore, to the cathodes of the triode'tubes 27 and 29. i The positive terminaliof the battery 30 is electrically connected to one. terminal of the primary coil of the transformer 28 the other terminal ofiwhich is electrically connected to the anode of the triode tube 27. The. positiveterminal of the battery 30 is also electrically connected to one terminal of the instrument 24 the other terminal of which is electrically connected to the anode of the triode tube 29. The secondary coil of the transformer 28 has one of its terminals electrically connected to the cathode of the triode tube 29 and its other terminal electrically connected to the grid electrode of the triode tube 29. One of the terminals of the coil 26 is electrically connected to the grid electrode of the ,triode tube 27. The other terminal of the coil 26 is electrically connected to the cathode of the triode tube 27.

'The electrical arrangement of triode electron tubes in the circuits herein-before described constitutes a two stage amplifier, of a well known kind, which functions in a manner to greatly amplify electrical potential differences impressed between the grid electrode and the cathode of" the triode tube 27, as evidenced by similar, butamplified, potential differences between the terminals of the instrument 24.

The arrangement of electrical circuits and apparatus hereinbefore described in connection with Fig. 1, is such that the condenser plates 1 are conductively joined together,

by means of the brushes 13, the brush holders 12, the inductancecoil 26, and the conductor 11, twice during each revolution of the shaft 4. The time intervals during which the ,plates 1 are not" conductively joined are of equal duration, it being assumed that the speed of rotation of the motor 5-is constant.

In Fig. 2 the insulating, or dielectric, arm 2 is in the form of a ring supported by the motor shaft 1. by means of the insulating.

spider 3. The conductor ll-isenclosed by the insulating tube 10. A housing, consisting of the cylindrical wall 7 bottom 6 and top 8, enclose the rotating condenser having plates 1 (one only of which is in view in the figure), driving motor 5 and the conductor 11. An electron tube amplifier is contained in the housing 23. The numeral 25 representsthe controlling switches for the amplifier circuits. The conductor 11, with its supporting tube 10, may be rotated through an angle of one hundred and eighty degrees, in a plane parallel to the plane of rotation of the condenser plates 1, by means of the shaft 14, which-is rigidly attached to the insulator block 9, to which thecommon central oint of the conductor 11 and insulating tu e 10, is also rigidly attached. The

shaft 14 is driven by the gear 15, to which it is attached, and which carries the pointer 17. A worm 18, which engages the gear 15, is supported by bearings 19 and is driven through shaft 20 by means of crank 21 and handle 22. The pointer 17 is rigidly attached to the gear 15, and therefore to the shaft 14, with its longitudinal dimension at an angle of ninety degrees from, and in a plane parallel to that of the conductor 11.

conveyance the housing 23, and therefore to the conveyance upon which the entire device is mounted, is indicated by a graduated scale 16. The entire device is mounted n on the in a position wherein the pointer 17, when opposite the center of the graduated scale 16, is pointing in the direction of the head, and has its longitudinal dimension parallel to the fore-and-aft center line of conveyance. When the pointer is in this position the conductor 11 has, therefore, its longitudinal dimension in a position displaced ninety degrees from the fore-andaft center line of the conveyance, and consequently, ninety" degrees from the direction in which the conveyance is heading. The device is attached to the conveyance in such a manner as to permit the conductor 11 to lie in a plane substantially parallel to the earths surface.

Let it be assumed that the conductor 11 is moving in a plane parallel to the-surface of the earth and that its direction of motion is perpendicular to its greatest dimension, that is, to its length. Under such condition. an electromotive force will be generated within the conductor, proportional to the rate at which it cuts the vertical component I of the earths magnetic field and a corresponding'electrical potential difference will. be established between the outer extremities of the conductor. It is to be understood that the direction of the motion of the conductor l1, and its velocity relative to the earths surface, is that of the conveyance to which it is attached. Let V meters per second represent the velocity of the con veyance relative to the earths surface in a plane parallel thereto. If H maxwell per square centimeter is the intensity of the vertical component of the earths magnetic field; L meters the length of the conductor 11 which cuts the vertical component of the earths magnetic field in a direction perpendicular thereto; and E millivolts the difference of electrical potential generated between the extreme ends of the conductor 11 due to the rate at which it cuts such magnetic field; then 1 10E "FIT condenser plates 1 shall be of proper duration to permit the condenser having plates 1- to be charged, at the moment when electrical contact between the brushes 13 and plates. 1 is interrupted, to substantially the same electrical potential difference between its dates as that generated-in the condudtor .1, due to therate at .which it is cutting the 'ertical component'of the earths magnetic ield and which exists between the brushes .3 at the moment of such interruption. The -.lectrical potential difference, E, between the :ondenser plates 1 is, therefore, of substanially equal magnitude to the eleetromotive; iorcelgenerated in the conductor 11. but is in direction opposing any ele tric current )roduced by such electromotive-fo'rce, atthe noment when the electrical contact between ;he brushes 13 and plates 1 is interrupted. Remembering that the condenser plates 1 me rotating, with substantially (onstant angular velocity, about the center'of their driving shaft 4'; it may be 'seen that when they lave rotated through an angle of substantial- [y one hundred, and eighty degrees they are again in electrical contact with the brushes l3. The difference of electrical potential, E, between the condenser plates 1 is now in a direction to assist a current produced bythe electromotive force,"E,-generated in the manner'herein-before defined, in the conductor 11. A transient electric cdrrent will, therefore, be established in'the circuit consisting of the condu'tor 11, brush-holders 12, brushes 13, inductance coil 26 and condenser having plates 1; such current hav-' ing a maximum instantaneous value proportional to a transient electromotive-force in the circuit of 2E. This current may, de pending upon the magnitude of the resistance of the circuit, relative to the values of the inductance and capacitance' thereof, be eitheroscillatory oriion-oscillatory. 1 prefer to so proportion the constants of this circuit, as to cause the current therein to he oscillatory. I also prefer to so connect the terminals of the inductance coil 26 to.

the grid electrode and the cathode, respectively, of the triode electron tube 27, as to impress the maximum instantaneous potential difierence existing between the terminals of the coil and caused by the current therein, upon the-grid electrode and cathode of the tube, in such direction as to cause the grid electrode to be positive potential with respect to the cathode atthe instantof such maximum potential difierence.

The rate of decay 1n amplitude of the electrical potential, and current, 'in the cir- 'cuit discussed is; as is well known, established by the rate at which the energy in electrical form therein is radiated or is con;

verted into other forms. The succeedingamplitudes of the oscillatoryv train are, however,, functions of the initial potential amplitude, 2E. As the rate of decay, or decre 'ment, of the circuit may be made cpnstant, the potential variations impressed upon the.

grid electrode and cathode of the tube 27 are proportional to the initial potential amplitude, 2E, which in turn isproporticnalfto.v

standard United. ta

the velocity, of the conveyance as relative to the surface of the earth.

The amplitude of the current in the inductance coil 26, and therefore the potential difference between its terminals, will become approximately zero when the condenser, having plates 1, has again become charged to the electrical potential difference, between its plates, generated by; the conductor 11.

The, electrical contact between the brushes l3 and the plates l/will then again be interrupted, to be re-established when the plates 1 have rotated through a further angle of approximately one hundred and eighty degrees, and the cycle or events described repeated. I

' The difierences of electrical p'itential communicated to the terminals of the potential, or current, indicating instruihent 24 are pro portional t0,-but are of much greater magnitude than, the difierences of potential im-. pressed upon the grid electrode and cathode of the triode -tube 27, as has been hereinbefore explained. As the speed Of lQVOllb' 1 tion of the motor 5 is approximately constant the instrument 24:11151 to indicate the velocity, ance directly. u 1

As E is of maximum value for any velocity, V, when the conductor-11 is perpendicular to the course of the conveyance, it becomes'necessary to adjust the position of the conductor 11, as relative to the fore-andaft center-line of the conveyance, by means of the handle 22, to aposition where a maximum current, or potential, is indicated by of the conveyno be calibrated 1 the instrument 24. The position of the I ferent places'u on the earths surfare, as is well known. ecourse must, therefore, be

had to charts prepared by various govern-' mental agencies with a high degree of ac-- curacy, which showvdirectly, or furnish sufficient information to permit the derivation of, the required'value of field intensity at nearly all places upaon,'the surfase oi the earth. It should be noted that in the near-.vicinity of the earths magnetic equator the intensity ofthe, vertical component of theearths magnetic fiel is of insufficientmag'nitude for the purposes of this in venticrn.

As a practical example of the application of this invention, let it be assumed that an air-ship,i-'in the-approximate vicinity of Seattle, Washington, -United States of America, is proceeding upon a .compass course of thirty de ees indicated. by a Navy mariners compass-- After. correction {or the varialee - strument, when the pointer 17 is adjusted to a position twenty-fiv degrees to the left, or port, side of the center pointof the graduated scale 16. The true course of the airship is then three hundred and thirty-six degrees, that is,

azimuth reading. The velocity, V, of the air-ship, relative to the ground, is directly indicated by the position of the pointer of the instrument 24:, which may be calibrated to show such velocity in knots, geographical 'miles, or kilometers, per hour, or in any other system of units desired, provided that a value of H:0.5 (the approximate intensity in maxwells per square centimeter of the vertical component of the earths'magnetic field .in the locality specified) has been used in the formula 10E V: at

wherein the deflection of the pointer of the instrument 24 is a function of E. If a value of H other than 0.5 has been usedin the .process of calibrating'the instrument 24, say

H203, the value of H:0.5, for the locality involved, must be ascertained from a chart, hereinbefore mentioned, and the velocity indicated by the instrument corrected by multiplying it by three and dividing,

the product so secured by five. I

Let it be further assumed that the velocity, V, of the above example, is ten meters per second; and that the length of the conductor 11 is fifty centimeters. Then 5 and"E=.25

W= /V +i 2VP cos 25 s #100 +225 300 x2063 e 7.28

meters per second. Let X represent the angle included between the line of corrected compass bearing of the ships head (the apparent course of one degree) and the line of direction from which the wind is approaching. Then The component, of the tru course of the rection in which the conveyance is headed 'is easily determined by the use of a/compass, and, when the drift angle is known ship, due to the wind is, therefore.

It is obvious. that the application of my invention not only affords a means of ascertaining the true course and velocity, with respect to the earths surface, of aircraft as discussed in the above example; but, also, its use in conjunction with well known devices for measuring the velocity of the air-craft, with respect to the air, to-

gether with the exercise of simple mathematical processes, affords a means of resolving such true course and velocity into component courses and velocities due to forces applied to'the air-craft by the wind and the action of their propellers. It may be also readily understood that the principles of my invention and the method of its use may .be applied with equal facility to the science of navigation of water-craft, or of other conveyances, the true course and velocity,

the true course is easil determined.

It is also obvious t at many modifications, or changes, may be made in the shape,

kind and arrangement of the various parts without departin from the broad scope of theappended claims. It-is further apparent that other types "of amplifying relays may be used in place of the two stage electron tube amplifier herein shown and described. While I have shown and described a particular formand kind of apparatus,

1 do not desire to be limited, or restricted, in the broad scope of my invention, as described in the claims, to any specific structure of apparatus or its arrangement in elementary parts, the assemblage of which form the means of accomplishing the purposes hereinbefor stated in substantially,

the manner herein described.

Having set forth the nature of my in-' vention, anda means of accomplishing the purpose thereof, what I claim asinew and useful-and of my own invention, and demm to secure by Letters Patent is 1. The method of ascertaining the characteristics of motion of a body relative to the earth in a plane substantially parallel to the earth s surface which consists in inducing 1 an electromotive force proportional to the velocity at which the vertical component of the earths magnetic field is cut by said body and deducing said characteristics of motion from said electromotive force, the

hearing of the earths poles with respect to a fixed dimension of the bodybeing known.

2. The method of ascertaining the characteristics of motion of a body, in a plane substantially parallel to the earths surface,

relative to the earth, the bearing of the earths'poles with respect to a fixed dimension of the bodyrbeing known, which consists in generating an electromotive force by cutting the vertical component of the earthsmagnetic field at the velocity of the body and measuring said 'electromotive force.

3. The method of ascertaining the characteristics of motion of a body relative to the {3 earth, in a plane substantially parallel to the surface of the earth, the bearing of the earths poles with respect to a 'fixed dimension of the body being known, which COD, 3 nets in measuring the electromotive forces generated in an electrical circuit carried on said body, said forces being generated by, and proportional to the velocity-of said body relative to the vertical co-mponent of the earths magnetic' field.

4. The methogl of ascertaining the characteristics of moti n of a moving body, relative to the earth, in a plane substantially para-lv lel to the surface of the earth, the bearing of the earths poles with respect to a fixed dimension of the body being known, which consists in generating electromotive forces, proportional to, the rate at which the vertical component of the earths magnetic field is cut by said moving body and utilizing said electromotive forces to indicate the velocity of movement of said body.

5. The method of ascertaining. the characteristics of motion of a body ina plane substantially parallel to the surface of the earth, relative to the earth, which consists in generating electrical potentiahdifi'erences between points in an electrical conductor carried by said body, said electrical potential differences being, generated by, and proportional to, the velocity of said body relative to the vertical component of the earths magnetic field, and deducing from said electrical potential differenbes the velocity of said body, the hearing of theearths poleswith respect to a fixed dimension of the body being known.

eeaaeo the earth.

plane. v

.1 6. Thembthod of'ascertaining'the characteristics of motion of'a body in a plane substantially parallel to the surface, of the earth, relative to the earth, which consists,

in generating electrical potential differences between points in anelectrical coniluctor cariied by said body, said electrica potential differences being, generated by, and proportional to} the velocity of said body relative to the-vertical component of the ,earths magnetic field, amplifying said electrical potential differences, and using said amplified electrical potential difi'erences to find I the velocity of said bodyfthe bearing of the earths poles with respect to a fixed dimen- Q sion of the body being knoyvn.

7. Devices for a conveyance, embodying an electrical conductor arranged on said conveyance for movement'over the earths surface in a plane substantially parallel to 3 the earths surface to thereby cut the vertical component of the earths magnetic field whereby electrical potential difierences will be generated between different points of said electrical conductor and means actuated by said differences of potential for determining the speed and drift of movement of said conveyance. 1

8. Devices of the class described fpnuse on a conveyance, embodying an electrical conductor movable with the conveyance-1n 9. Devices arranged to be carried bye conveyance, movable relative to the earth, for indicating the movement of said/conveyance, in a plane substantiallyparallel to the surface of the'earth, embodying Ia); 115

electrically conductive element carrie said conveyance and arranged to cut the vertical component of the earths magnetic field at the velocity of the conveyance whereby electromotive forces will be generated there-' 0 in, and means connected with said electrical ly conductive element for utilizing said'electromotive forces to determine the speed and drift of movement of said conveyance infisaid 10. Devices arranged to be carried by, a conveyance, movable relative to the earth, for indicating thespeed and drift of said conveyance,in a plane substantially parallel to the surface of the, earth, embodying an 130 electricallyconductive element arranged to cut the vertical component of the earths magnetic field whereby electromotive forces will be generated therein, means for adjusting said electrically conductive element to find the position in which said electromotive forces are of maximum value, and into the surface 0 dicating. devices connected with said electrically conductive element and arranged to be actuated by said electromotive forces.

11. Devices arranged to be carried by. a conveyance, movable relative to the earth, for indicating the speed and drift of said conveyance, in a plane substantially parallel to the surface of the earth, embodying an electrically conductive element arranged to cut the vertical component of the earths magnetic field whereby electromotive forces will be generated therein, means for amplifying said electromotive forces, and indicating devices arranged to be actuated by said amplified electromotive forces.

12. Devices arranged to be carried by a conveyance, movable relative to the earth, for indicatingthe speed and drift of said conveyance in. a plane substantially parallel the earth, embodying an electrically conductive element arranged to cut the vertical component of the earths magnetic field: and to thereby have difi'erences of electrical potential generated between difl'erent points thereof, an electrical condenser having terminals arran ed to make electrical connections'alternate with said different points ofsaid electrical y conductive element whereby said condenser will be alternately charged and discharged and an indicating device arranged to be actuated by the electric current produced in said electrically conductive element. h e

13. Devices arranged to be carried by a conveyance, movable relativeto the earth, for. indicating the speed and drift of said conveyance in a plane substantially parallel to the surface of the earth, embodying an electrically conductive element arranged to cut the vertical component of the earths magnetic field and to thereby have difierences of electrical potential generated between difi'erent points thereof, an electrical condenser having terminals arran ed to make electrical connections alternate with said difierentpoints of said electricall y conductive element whereby said condenser will be alternately charged and discharged, means for adjusting said electrically conductive element. to a position in which said differences of electrical potential are of mar:- imum value, and an indicating device arranged to be actuatedby the electric current produced in said electrically conductive element. i

14. Apparatus of the class described, em-

'b'odying an electrically conductive element 'adjustably supported in a normally horizontal plane, and arranged for movement in a unipolar magnetic field, an electrical condenser, having terminals arranged to make electrical contact alternately with the extremities of said electrically conductive element, means for rotatably mounting said condenser, and indicating means governed by the electric current roduced in said electrically conductive e ement .in res onse to movement of the same in said unipo ar magnetic field.

15. Apparatus of'the class described, em-

relay for amplifying electric current gener.

ated in said electrically conductive element, and an indicating device arranged to be operated by said amplifiedelectric current.

16. A paratus for determinin the drift of a bo y in a plane substantial y horizontal relative to the surface of the earth, em'

bodyin an electrical conductor carried by the b0 y and arranged to have electrical potential difi'erences generated between diiferent points of the same by "the movement of such body relative to the vertical component of the earths magnetic field, means for adjusting said electrical conductor in said substantially horizontal plane to a position wherein the shortest line in said plane joining said points is substantially at right angles to the path of said body in said plane, ,whereby diflerences of potential of maximum value are obtained and means for determining theosition of said conductor relativeto said ody when said differences of otential are of maximum value.

1 In apparatus of the class described an electrical conductor arranged for movement in a unipolar magnetic fie d, and means for .determining diiferences of electrical potential enerated between oints in said electrica conductor, embo ying an electrica condenser having terminals arranged to connect electrically with said points of said electrical conductor and their to reverse said electrical connection, and means for measuring the electric current produced in said.

conductor by the discharge and subsequent charge of said condenser in conjunction with the electromotlve force generated -in said conductor by its motion in said magnetic field. v

FREDERICK GRANT SIMPSON. 

